A pairing between devices is an indispensable element in an Ad-Hoc network environment in which a variety of devices are connected for use. The Ad-Hoc network does not require an infrastructure network that is generally needed to communicate between respective devices which are members of the networks. In other words, the Ad-Hoc network does not necessary to equip repeaters between the devices such as routers, AP (Access Points), or the like that constitutes the network. The Ad-Hoc network can be established once the partial connection between the respective devices in the Ad-Hoc network, that is, a pairing between a current specific device and another device is performed.
In recent, the supply of portable devices and the communication using these portable devices are in a trend to be increased. Accordingly, in an environment without having an infrastructure network for communication between devices, the Ad-Hoc network becomes more and more important due to its ability to provide the communication between the devices anytime and anywhere. Examples of the Ad-Hoc network may be the data transfer between one smart phone and the other smart phone, the screen linkage between a smart phone and a tablet device or smart TV, and the like.
Because the infrastructure network does not exist in an Ad-Hoc network environment, it is important to generate and manage a security key to be used in the communication security between devices. There is no trusted authority on the Ad-Hoc network environment generally and thus a method to share a security key between devices is considerably limited. Meanwhile, an RSA (Rivest Shamir Adleman) method, which is one of public key encryption methods, is widely used to provide secure communication between devices. This algorithm employs two large numbers (typically 140 digits or more), constituting one public key and one private key by multiplying and further calculating the two numbers. The public key and the private key can be used to encrypt and decrypt data for communication. The RSA method has a shortcoming in that it requires a large amount of computation. It takes as little as 20 minutes to as long as several minutes for a Pentium-level computer to generate the public key and the private key. In addition, the RSA method also requires a large amount of calculation in decryption. However, it is not easy for portable devices to secure a higher computing power against a battery issue, handheld issue, heat generation issue, and the like. Therefore, the RSA method requiring a mass calculation may not be suitable for security solution to the Ad-Hoc network.
On the other hand, there are increased cases that a user perform tasks on a terminal of a company or a public institution using a file received or downloaded from an external device or a data server. Since a terminal with which a user performs tasks may be commonly used by other persons in the future, there occurs a need to protect privacy of task contents. In the service scheme embodied in an available operating system (OS), it is necessary to store work contents in a local storage space such as a hard disk. Although a user deletes the work contents after completing the work, there necessarily remain physical traces, and therefore, it is possible to recover them using various recovery methods. Accordingly, there is a problem that privacy of data may not be guaranteed.